γγ→ℓ+ℓ− and γp→ϒp→ℓ+ℓ−p at CMS

Exclusive dilepton events are characterized by the presence of two back-to-back leptons, and no other detector activity above threshold. In pp collisions in the CMS experiment, this signature can result from two-photon interactions (γγ→ℓ+ℓ−) or ϒ photoproduction (γp→ϒp→ℓ+ℓ−p). In the early data from the LHC, these events will provide a calibration sample for luminosity and lepton reconstruction studies, and allow studies of diffraction and QCD.